A brass measuring tape is correct at 20 degree Celsius. The value obtained when the length of a field is measured with the rule at 50 degree Celsius appears to be 70.5m. what is the true length of the field Linear expansivity of brass =1.8 ×10 raise to power minus five per Kelvin.
since K = C + 273 change in centigrade is the same as change in Kelvin
change in L / L = (50-20)(1.8 *10^- 5)
change in L = 70.5 (30)(1.8*10^-5)
= 3780 * 10^-5 = 0.04
so 70.5 - 0.04